1. Technical Field
This application relates to UMTS (Universal Mobile Telecommunications System) in general, and to a method and apparatus for processing messages in a universal mobile telecommunications system in particular.
2. Description of the Related Art
UMTS is a third generation public land mobile telecommunication system. Various standardization bodies are known to publish and set standards for UMTS, each in their respective areas of competence. For instance, the 3GPP (Third Generation Partnership Project) has been known to publish and set standards for GSM (Global System for Mobile Communications) based UMTS, and the 3GPP2 (Third Generation Partnership Project 2) has been known to publish and set standards for CDMA (Code Division Multiple Access) based UMTS. Within the scope of a particular standardization body, specific partners publish and set standards in their respective areas.
Consider a wireless mobile device, generally referred to as user equipment (UE), that complies with the 3GPP specifications for the UMTS protocol. The 3GPP 25.331 specification, v.3.15.0, referred to herein as the 25.331 specification, addresses the subject of UMTS RRC (Radio Resource Control) protocol requirements between the UMTS Terrestrial Radio Access Network (UTRAN) and the UE.
The 25.331 specification describes generic processing of information elements (IEs) that are included in protocol messages. Section 8.6.3.4 describes the processing of the ‘Ciphering Mode Info’ IE and includes clauses that describe the IE ‘Ciphering Activation Time for DPCH’ that is an optional element with the ‘Ciphering Mode Info’ IE. This section of the specification is worded to ensure that the ‘Ciphering Activation Time for DPCH’ IE is present when the message being processed is a Security Mode Command message and there are Transparent Mode (TM) radio bearers in existence. Furthermore, section 8.1.12.2 of the 25.331 specification enforces behaviour on the UTRAN to state that it must include this IE in the Security Mode Command message when TM radio bearers exist.
Other messages exist that can include the ‘Ciphering Mode Info’ IE, in addition to the Security Mode Command message. The inventors have realised that conditions may exist in relation to these messages where the ‘Ciphering Mode Activation Time for DPCH’ IE would be required for the UE to exhibit logical behaviour, but no mechanism is specified for ensuring that it is available. These messages include the five reconfiguration messages specified in section 8.2.2, the Cell Update Confirm and URA Update Confirm messages described in section 8.3.1 and the UTRAN Mobility Information message specified in section 8.3.3 of the 25.331 specification.